Ultra high frequency oscillation circuit



Nov. 10, 1936. c. W/HANSELL 0 ULTRA HIGH FREQUENCY OSCILLATION CIRCUIT Filed March 20, 1934 INVENTOR C.W. HA SELL V. I A

)RNEY Patented Nov. 10, 1936 PATENT OFFICE HIGH FREQUENCY OSCILLATION Clarence W. Hansell, Port Jefferson, N. 1., assignor to Radio Corporation of America, a cor- -poration of Delaware Application March '20, 1934, Serial No. 716,485

9 Claims. (Cl. 179-471) This invention relates to ultra short wave oscillators and to circuits for such oscillators.

In my United States Patent No. 2,001,133, granted May 14, 1935, there has been disclosed a novel type of ultra high frequency oscillator whereby there may be generated high frequencies of the order of 3,000 kilocycles or higher. In this arrangement oscillations are produced by influencing a stream of electrons emanating from a 10 cathode to travel in a curved path and to cross upon itself so as to obtain a periodically interrupted stream of electrons. This mode of operation, which is quite similar to the functioning of the air stream in an air whistle, has been designated as the electron-whistle principle. In general, according to one embodiment described in my United States patent supra, the oscillator comprises a hot cathode and an anode at opposite ends of a tube-like affair to the anode end of so which is connected a curved shell. A voltage applied between the anode and cathode causes the electrons emitted from the cathode to travel toward the anode with an accelerating velocity in such manner that when the electrons enter the shell they have, under proper conditions, such a high velocity that they flow on past the anode due to their momentum. If the velocity has been made sufiiciently great, and the shell has the same potential as, or a more negative potential than the cathode, the repulsion between the shell and the electrons will cause the stream to bend aroundthe shell in a loop before arriving at the anode. In order to reach the anode, however, the electron stream is arranged to cross its own path at the anode end of the tube-like affair, and to thus interrupt the stream entering the shell, due to the mutual repulsion between electrons. The stream remains interrupted until the electrons in the shell have all passed by, after which the electron stream is again admitted to the shell and the cycle of operations repeated.

The present invention is based on the same general principle described above, namely that of producing radio frequency oscillations by the motions and the mutual forces acting between the electrons within the vacuum tube; in other words, the oscillator does not require variations of potentials on the electrodes to carry out the controlling action necessaryfor oscillation, but

depends solely upon the action of the electron stream itself. In general, the invention comprises an alternative arrangement to that of the above mentioned patent for producing oscillations and differs therefrom in two ways; first, in

the mechanical arrangement employed, and secondly in the manner in which the resultant oscillations are obtained. In the present case, the electrons are made to travel over paths forming the figure 8 in such a way that the electrons are deflected first to one side of a center line 5 and then to the other side, such that the total volume occupied by the electrons in producing oscillations is symmetrical about the plane of zero deflection, in consequence of which the oscillations are known as "push-pull". 10

A feature of the invention lies in the symmetrical deflecting electrode arrangement for causing the electron stream emanating from the oathode to follow the flgure 8.

A more detailed description of the invention 5 follows in conjunction with the single figure of the drawing which illustrates schematically the oscillator of the invention in a complete radio transmitting circuit.

Referring to this figure more specifically, there is shown, in cross-section, a vacuum tube oscillator comprising an evacuated envelope I preferably of glass, containing within it an electron emitting cathode 2 supported from a stem 3 and heated from an external battery or other suitable source Ii, an anode 4 in the form of a grid, which is supported from a stem 5 oppositely disposed with respect to the stem 3, and a deflector 6 on a metal cylinder 8 located on stem 3 and symmetrically positioned with respect to the an anode 4. Grid-like anode B is maintained at a positive potential by a battery I located externally of the envelope I, and serves to accelerate the electrons emanating from the cathode and finally to collect the electrons after they have passed through the mesh of the anode and have been deflected. The deflector 6 is preferably made ofmetal and is herein shown maintained at a negative potential with respect to the cath ode 2 by means of a lead 9 and resistor l0. Also contained within the envelope is a shield l2 located intermediate the stem 5 and grid-like anode 4 for protecting the anode stem from electron bombardment.

Any suitable utilization circuit, such as an 45 antenna l2, may be coupled to the output of the device through a transformer IT, as indicated. In this arrangement the output frequency is double the fundamental oscillation frequency and corresponds to the second harmonic of the funda- 5o mental frequency. Although the form of coupling shown in the drawing is preferred, other means of coupling may be used and will readily suggest themselves to those skilled in the art, for example, the use of straight conductor leads close- 55 to a movable slider M which is arranged to glide over the anode lead i5 extending between the anode and its source of supply 1. If an antenna circuit is utilized, tuning elements such as trombone slides l6, It may be connected in the transmission line connecting the antenna to the output circuit for tuning the line to the output frequency. Of course, where it is desired to have radiation take place directly from the vacuum tube oscillator, the antenna circuit will be dispensed with and the tube will ordinarily be placed at the focus of a reflector system, not shown, so that radiation lit the desired direction will be increased. Radiation may also be increased by dimensioning the anode 4 to make itsnatural period of electrical oscillation come near' to the oscillation frequency or, instead, the deflector 6 may be tuned to the oscillations. If desired, an external radiator, 01" a transmission line and radiator, may be coupled to the anode 4 or the deflector 6. andtuned to the oscillation frequency, or a harmonic of it.

The operati n of the'deyiceis asioilows:

When the athode of the vacuum tube oscillator device is energized from the source Ii, negatively charged electrons are emitted which are attracted toward the positively charged gridlike'anode 4. These electrons travel in a substantially straight line but if, for any reason, this beam of electrons is displaced slightly from the center of the anode, a condition which will happen automatically in practice, a predetermined electron current will flow to one side of the center of the anode and traverse a curved path inside the deflecting electrode in such manner as to return/t the original path of the electron streamleaving the cathode. Deflector 6, as has been mentioned before, is charged negatively to eifect this result. If desired, however, it will readily be apparent that an alternative type of construction than the metal electrode may be used, for example, an insulating shell made of glass whic it has been found, will act just as well asz xetal shell; in fact, the insulating shell will hav advantages in that certain areas of the shell may be more negatively charged by the electrons so that the distribution of the negative charge is more in accordance with that required to prevent the impinging of large numbers of electrons at various points. In such a case, various portions of the inside of the deflecting insulator wil automatically assume the correct potentials Eor suitable operation of the device. In using gl ss, however, it will usually be necessary to coat the surface with carbon or other suitable material for lessening secondary emission from the surface. To continue with the operation of the circuit, the returning electrons will deflect the electron stream leaving the cathode to the opposite lide of the deflecting electrode and the stream will remainon this side until its front has traversed the curved path of the deflector electrode and returned again to the vicinity of the cathode. The returning stream will then push the stream of electrons newly issuing from the oath dc to the opposite side of the tube and the proce s ,will be repeated at a frequency corresponding tothe time of travel of the electrons around the defl ctor electrode. Thus the electronstream ms the other of a figure 8, and this constitutes an oscillation of electron current, energy from around first one end and then which may be radiated directly or by means of a utilization circuit, as shown, through suitable coupling conductors to an antenna system.

If it is desired to modulate the output of the oscillator, signals to be transmitted may be applied in such manner that the potentials on either the anode 4 or the deflector electrodes, or both, are varied so as to produce keying or modulation of either amplitude or frequency, or both. In the drawing there has been shown means by which speech waves applied to a microphone l8 and amplified by apparatus l9, shown conventionally in box form, may be applied to a modulator 20 to modulate the oscillations obtained from the oscillator tube by means of the Heising method of modulation. By this method the potential applied to the anode is-varied in accordance with the variations of the speech wave" Of course, the modulations may also be accomplished through changes of potential on the deflecting electrode 6 in accordance with the signal waves to be transmitted. For this purpose there is herein shown a keying relay II which is responsive to telegraph signals applied to a key 22 to interrupt the circuit extending from the deflecting electrode to the cathode. It will thus be seen that the oscillations may be modulated or keyed, either by speech, music or tone signals, etc., or by any combination of these alternatively or simultaneously.

It will be understood, of course, that the invention is not limited to the precise arrangement of parts shown since various other organizations may be employed without departing from the spirit and scope of the invention, for example, sources of alternating current energy may be employed instead of the batteries shown, and the cathode may have other forms than that indicated, and if desired may be of the indirectly heated type.

I claim:

1. An electron discharge device comprising an evacuated envelope having within it a cathode, an anode in the form of a grid, and a deflecting electrode symmetrically positioned with respect to said anode and cathode, said deflecting electrode extending from points near said cathode outwardly toward said envelope beyond the edges of said anode to points on theother side of said anode for curving the stream of electrons emitted by said cathode and passing through said anode so as to cross its own path at an angle.

2. An electron discharge device comprising an evacuated envelope having within it a cathode, a plate-like anode in the form of a grid, and a deflecting electrode symmetrically positioned with respect to said anode and cathode, said deflecting anode having flared portions which substantially surround said anode, each of said portions extending from a point near said cathode outwardly beyond one edge of said anode to a point on theother side of said anode near the plane of zero electron deflection whereby the stream of electrons emitted by said cathode and passing through said anode are deflected by said flared portions so as to cross its own path at an angle and influence the direction of travel of said stream.

3. An electron discharge device comprising an evacuated envelope having within it a cathode, an anode in the form of a grid, a metallic deflecting electrode symmetrically positioned with respect to said anode and cathode, said deflecting electrode extending from points near said cathode outwardly toward said envelope beyond the edges of said anode to points on the other side 01' said anode, and means for maintaining said anode at a positive-potential and said deflecting anode at a negative potential with respect to said cathode, whereby the stream oi electrons from said cathode passing through said anode are caused to travel in a curved path so as to cross itself at an angle.

4. An electrode discharge device comprising an evacuated envelope having within it a cathode, an anode in the form of a grid, and a deflecting electrode symmetrically positioned with respect to said anode and cathode, said anode and deflecting electrode being supported from stems on opposite sides ofsaid "envelope, said deflecting electrode extending from points near said cathode outwardly toward said envelope beyond the edges of said anode to points on the other side of said anode for curving the stream of electrons emitted by said cathode and passing through said anode so as to cross its own path at an angle, and a shield intermediate said anode and its supporting stem for protecting said stem from electron bombardment.

5. In combination, an electron discharge device oscillator comprising an evacuated envelope having within it a cathode, an anode in the form of a grid, a metallic deflecting electrode symmetrically positioned with respect to said anode and cathode, said deflecting electrode extending from points near said cathode outwardly toward said envelope beyond the edges of said anode to points on the other side of said anode, means for maintaining said anode at a positive potential and said deflecting anode at a negative potential with respect to said cathode, whereby the stream of electrons from said cathode passing through said anode are causedto travel in a curved path so as to cross itself at an angle, and individual means for varying the potential of said anode and deflecting electrode in accordance with diiferent signals to be transmitted.

6. An electron discharge device comprising an evacuated envelope having within it a cathode, an anode in the form of a grid. a deflecting electrode symmetrically positioned with respect to said anode and cathode, said deflecting electrode extending from points near said cathode outwardly toward said envelope beyond the edges of said anode to points on the other side of said anode for curving the stream of electrons emitted by said cathode and passing through said anode so as to cross its own path at an angle, and means for maintaining said anode at a positive potential with respect to said cathode.

7. An electron discharge device comprising an evacuated envelope having within it a cathode, a flat disc-like anode in the form of a grid, said anode and cathode being supported from stems on the opposite sides of said envelope, an openended cylinder surrounding said cathode and mounted on the stem supporting said cathode, a deflecting electrode symmetrically positioned with respect to said anode and cathode attached to said cylinder, said deflecting electrode extending from points on said cylinder near said cathode outwardly toward said envelope beyond the edges of said anode to points on the other side of said anode, whereby electrons travelling from said cathode to said anode on either side of a center line between said anode and cathode will be deflected by said deflecting electrodes.

8. In combination, an electron discharge device comprising an evacuated envelope having within it a cathode, an anode in the form of a grid, and a deflecting electrode symmetrically positioned with respect to said anode and cathode, said deflecting electrode extending from points near said cathode outwardly toward said envelope beyond' the edges of said anode to points on the other side or said anode for curving the stream of electrons emitted by said cathode and passing through said anode so as to cross its own path at an angle, and an output circuit coupled to said anode.

9. The method of producing high frequency oscillations which comprises propelling a stream of electrons in a direction along a confined path, making said stream of electrons cross upon its own path at an angle to change the direction of travel of said stream to another conflned path, and again making said stream cross upon its own path at an angle. whereby said stream is alternately propelled periodically along said confined paths.

CLARENCE W. HANSELL. 

